Finite Element Analysis Evaluating Function Of LCP System .
International Journal of Pharma Medicine and Biological Sciences Vol. 8, No. 3, July 2019Finite Element Analysis Evaluating Function ofLCP System for Osteoporotic Humerus FractureJung-Soo Lee, Eunji Kim, Kwang Gi KimGachon University & Gachon University Gil medical Center /Dept. of Biomedical Engineering & Medical DevicesR&D Center, Incheon, Republic of KoreaEmail: jsmech@nate.com, eunjimd@gmail.com, kimkg@gachon.ac.krYong-Cheol YoonOrthopedic Trauma Division, Trauma Center, Gachon University College of Medicine, Incheon, Republic of KoreaEmail: dryoonyc@gmail.comand greater tubercle. In addition, other studies on LCPand locking screws also chose 3 parts fracture as the mainsubject as well [2-3]. Thus, the type of osteoporoticfracture model is defined as a 3 parts fracture in this study.Abstract—In this study, we developed a 3 parts fracturemodel of osteoporotic humerus by reconstructing the fourstructures of the humerus (cortical bone, trabecular bone,articular cartilage, sub-chondral) using a CT image for 3DCAD modeling. 3D CAD modeling of the fractured humerusand locking compression plate (LCP) system were done withthe use of SolidWorks 2017.Finite element analysis (FEA) of the osteoporotichumerus 3 parts fracture, LCP system was analyzed byANSYS Workbench 19.0, and the stress such as Maximumshear stresses on locking screw-cortical bone interface area,Maximum von Mises stresses at LCP and LCP-lockingscrew assembly was obtained with FEA.In torsion force applied load condition, the stressoccurred in with calcar screw was 50% to 200% lesser thanwithout calcar screw, effect of calcar screws was confirmed.(a)Index Terms—finite element analysis, proximal humerus,osteoporosis, fracture, LCP systemI.(b)Figure 1. (a) Anterior-posterior view of a Neer 3 parts fracture throughthe surgical neck and greater tuberosity. Image of osteoporotic humerusfracture [3], (b) 3 parts fracture CT 3D image on PACS.INTRODUCTIONB. 3D Model Obtained Form CT ImageProximal humerus fracture account for about 15% ofthe population over age 50 and incidence of osteoporosisincreases in parallel with the number of elderly peopleand as a result, proximal humerus fracture rises.LCP system offers excellent treatment results inproximal humerus fracture fixation [1].This study deals with FEA to evaluate the function andeffect of LCP system and calcar screws. The purpose ofthis study is to propose surgical treatment criteria usingan LCP system in patients with proximal humerusfractures with severe osteoporosis.II. MATERIAL AND METHODFigure 2. High-resolution CT images of humerus on PACS.A. Analysis of the Clinical Radiology DataFig. 1 shows the result of high-resolution CT imaginganalysis of 50 patients ( 60 years old) with osteoporoticfractures. The fractures obtained from the figure weremostly 3 parts comminuted fractures of a surgical neckWe collected high-resolution CT image from the localPACS (Picture archiving and communication system) ofGachon University for 3D model-based FEA. Of these,four image data were selected for 3D modelingreconstruction by analyzing four structures of thehumerus (cortical bone, trabecular bone, articularManuscript received January 16, 2019; revised June 12, 2019. 2019 Int. J. Pharm. Med. Biol. Sci.doi: 10.18178/ijpmbs.8.3.86-9086
International Journal of Pharma Medicine and Biological Sciences Vol. 8, No. 3, July 2019cartilage, sub-chondral) and saved as a DICOM formatfiles.ROI (Region of interest) was drawn on DICOM filesand evaluated with Analyze 11.0 program. These weresaved as OBJ format files and 3D model was obtainedwith Meshmixer program.edited and assembled for FEA 3D modeling withcomputer-aided design (CAD) - SolidWorks 2017(SolidWorks Corp., Dassault Systemes, Concord, MA,USA) and then four humerus 3D modeling werecompleted from four CT data.Samples of the LCP system (PHILOS, Synthes,Oberdorf, Switzerland) were supplied and these werecharacterized by 3 material constants of Young's modulusand Poisson's ratio. 3D CAD models of LCP system weremodeled using SolidWorks 2017.After reviewing the surgical cases of LCP and lockingscrews [4], one of the most suitable humerus 3D modelsfor LCP attachment was selected as shown in Fig. 6.Figure 3. ROI of humerus with Analyze 11.0.Figure 6. Surgical case of LCP and locking screw and 3D CAD model.Figure 4. 3D model reconstruction with Meshmixer.III. RESULTSC. 3D CAD Model for FEAA. Finite Element ModelFigure 5. 3D modeling of four reconstructed structures of the humerus(cortical bone, trabecular bone, articular cartilage, sub-chondral) withSolidWorks 2017.Figure 7. A 3 parts fracture (surgical neck of humerus and greatertubercle) and final two type (model A: with calcar screw, model B:without calcar screw) of 3D CAD model for FEA.Four structures of the humerus (cortical bone,trabecular bone, articular cartilage, sub-chondral) were87
International Journal of Pharma Medicine and Biological Sciences Vol. 8, No. 3, July 2019Osteoporotic fracture model was created to reproducethe majority of fracture, which is 3 parts fracture (surgicalneck of humerus and greater tubercle) [3, 5]. Also, finaltwo types of 3D CAD model (model A: with calcar screw,model B: without calcar screw) were made and thenimported to ANSYS Workbench 19.0 (ANSYS, Inc.,Canonsburg, PA, USA) for FEA.plate; screw and cortical bone and trabecular bone andsub-chondral [10].The distal segment of the humerus shaft was fixed toprovide support condition. In addition, shear force, andtorsion were applied to the models as a load condition.For shear force, 500N loads oriented vertically in thecoronal and sagittal planes were distributed onto theproximal humeral head and the angle of inclined 20 . Theshear force simulated the force that a proximal fracturesite would experience while the patient was rising out ofa chair or crutch weight-bearing [2]. To simulate rotation,a 200Nmm torque was applied to the proximal humeralhead around the axis of the humerus shaft as shown in Fig.9.B. Element Type and MeshingA SOLID187 element type that could be used todevelop the discretization of the humerus model was used[6]. This element type is composed of 10-node quadratictetrahedral elements with three degrees of freedom [7].The current study used humerus 7mm, LCP 3mm,locking screw 1mm as the mesh planning element sizerespectively and the total nodes and elements were:655,137 and 362,175 (model A), 641,952 and 354,841(model B).Figure 9. Support and load condition (shear force and torsion).E. FEA and ResultMaximum shear stresses on locking screw-corticalbone interface area, Maximum von Mises stresses at LCPand LCP-locking screw assembly was obtained with FEA.a. Load condition (shear force 500N / 20 )Figure 8. FEA model A and model B after meshing with Solid 187element.C. Material PropertiesFEA model was assumed as isotropic and linear elasticmaterials. Young’s modulus and Poisson’s ratio wasapplied to four structures of osteoporotic humerus(cortical bone: E 12GPa, v 0.3, trabecular bone:E 250MPa, v 0.3, articular cartilage: E 2MPa, v 0.3,sub-chondral: E 3.5GPa, v 0.3) respectively and havebeen referred to the related references [8].LCP system was made form titanium alloy(LCP(Titanium): E 110GPa, v 0.3, locking screw(Ti6Al-7Nb): E 105GPa, v 0.3, cortex screw(TiCP): E 103GPa, v 0.3).D. Boundary ConditionContact interactions between humerus shaft, greatertubercle fragment & head of humerus were defined usingsurface-to-surface finite sliding with a coefficient offriction of 0.3 [9].Contact condition between four structures of thehumerus (cortical bone, trabecular bone, articularcartilage and sub-chondral) was bonded respectively.LCP system defined as no movement along theinterfaces of screw and surrounding bone; screw andFigure 10. The Maximum shear stresses on locking screw-cortical boneinterface at head of humerus.The Maximum shear stresses on locking screw-corticalbone interface at head of humerus was 66.842MPa(model A) and 65.399MPa (model B) as shown in Fig. 10.Maximum von Mises stresses of LCP at cortex screwholes was 94.401MPa (model A) and 103.04MPa (model88
International Journal of Pharma Medicine and Biological Sciences Vol. 8, No. 3, July 2019B) were shown in Fig. 11. Maximum von Mises stressesof LCP and locking screw assembly at the lowermostlocking screw was 113.59MPa (model A) and 109.35MPa(model B) as shown in Fig. 12.The Maximum von Mises stresses of LCP and lockingscrew assembly at right calcar screw was 6.0735MPa(model A) and at the back of cortex screw holes was9.6651MPa (model B) as shown in Fig. 15.Figure 11. Maximum von Mises stresses of LCP.Figure 14. Maximum von Mises stresses of LCP.Figure 12. Maximum von Mises stresses of LCP and locking screwassembly.Figure 15. Maximum von Mises stresses of LCP and locking screwassembly.b. Load condition (torsion 200Nmm)The Maximum shear stresses on locking screw-corticalbone interface at head of humerus was 2.3912MPa(model A) and at humerus shaft was 5.5864MPa (modelB) as shown in Fig. 13. Maximum von Mises stresses ofLCP at the back of right calcar screw was 5.0035MPa(model A) and at the back of cortex screw holes was9.6651MPa (model B) as shown in Fig. 14.IV. DISCUSSION & CONCLUSIONFEA of the osteoporotic humerus 3 parts fracture, LCPsystem was analyzed by ANSYS Workbench 19.0, andthe stress such as Maximum shear stresses on lockingscrew-cortical bone interface area, Maximum von Misesstresses at LCP and LCP-locking screw assembly wasobtained with FEA.The effect of calcar screws in shear force applied loadcondition was minimal. Also, the result of stressesapplied to FEA model with calcar screw (model A) weresimilar with the FEA model without calcar screw (modelB). The reason for the minimal difference is assumed tobe a simple axial force application of which is an angle of20 inclination. However, in torsion force applied loadcondition, the stress occurred in model A was 50% to200% lesser than model B, and the function and effect ofcalcar screws was confirmed.We will further work to compare strength withpresence or absence of calcar screw under severalconditions, analyze and improve the accuracy of theFigure 13. The Maximum shear stresses on locking screw-cortical boneinterface at head of humerus (model A) and humerus shaft (model B).89
International Journal of Pharma Medicine and Biological Sciences Vol. 8, No. 3, July 2019with a medial gap: A finite element analysis,” Acta Orthopaedicaet Traumatologica Turcica, vol. 49, no. 2, pp. 203-209, 2015.effect of calcar screw with an additional FEA. Also,analyze different factors such as axial or torsion forceaffecting the results for more realistic condition.Jung-Soo Lee received his B.S in mechanicalengineering from Hongik University, Seoul,Republic of Korea in 2002. He currently work forresearch engineer at department of biomedicalengineering in Gachon University and medicaldevices R&D center, Gachon University Gilmedical center, Incheon, Republic of Korea. Hisinterests are designing surgical robots & medicaldevice, hydraulics system and structural &thermal analysis of FEA.ACKNOWLEDGMENTThis work was supported by the Gachon Univ. GilMed. Center research grant funded by the “Developmentof FEM simulator evaluating function of support bonescrews for proximal humerus fracture” (2017-5295).REFERENCES[1]C. H. Park, S. H. Park, and J. S. Seo, “Internal fixation ofproximal humerus fracture with locking compression plate,” J.Korean Shoulder and Elbow Soc., vol. 12, no. 1, pp. 44-52, 2009.[2] Y. He, Y. Zhang, Y. Wang, D. Zhou, and F. Wang,“Biomechanical evaluation of a novel dualplate fixation methodfor proximal humeral fractures without medial support,” J.Orthopaedic Surgery and Research, vol. 12, no. 1, pp. 1-11, 2017.[3] I. Mendoza-Muñoz, Á. González-Ángeles, M. SiqueirosHernández, and M. Montoya-Reyes, “Biomechanical principlesused in finite element analysis for proximal humeral fractures withlocking plates,” Medical Science and Technology, vol. 58, pp.128-136, 2017.[4] C. J. Laux, F. Grubhofer, C. M. L. Werner, H. P. Simmen, and G.Osterhoff, “Current concepts in locking plate fixation of proximalhumerus fractures”, J. Orthopaedic Surgery and Research, vol. 2,no. 1, pp. 1-14, Sep. 2017.[5] P. Varga, L. Grünwald, J. A. Inzana, and M. Windolf, “Fatiguefailure of plated osteoporotic proximal humerus fractures ispredicted by the strain around the proximal screws,” Journal of theMechanical Behavior of Biomedical Materials, vol. 75, pp. 68-74,2017.[6] M. Eduard, V. Daniel V, B. Titi, and P. Horia-Alexandru, “Anovel implant regarding transcondylar humeral fracturesstabilization. A comparative study of two approaches,” ProcediaEng., vol. 69, pp. 1201-1208, 2014.[7] J. Wolff, N. Narra, A-K. Antalainen, et al., “Finite elementanalysis of bone loss around failing implants,” Mater Des, vol. 61,pp. 177-184, 2014.[8] P. Clavert, M. Zerah, J. Krier, P. Mille, J. F. Kempf, and J. L.Kahn, “Finite element analysis of the strain distribution in thehumeral head tubercles during abduction: Comparison of youngand osteoporotic bone,” Surgical and Radiologic Anatomy, vol. 28,no. 6, pp. 581-587, 2006.[9] E. M. Feerick, J. Kennedy, H. Mullett, D. FitzPatrick, P. McGarry, “Investigation of metallic and carbon fibre PEEK. fracturefixation devices for three-part proximal humeral fractures,” Med.Eng. Phys., vol. 35, pp. 712-722, 2013.[10] P. Yang, Y. Zhang, J. Liu, J. Xiao, L. M. Ma, and C. R. Zhu,“Biomechanical effect of medial cortical support and medial screwsupport on locking plate fixation in proximal humeral fracturesEunji Kim is a clinical researcher in theDepartment of Biomedical Engineering atGachon University, Seoul, Republic of Korea.She earned her B.S. degree in 2008 with a humanbiology major and had her M.D. degree in 2012.Her main interests lie in the biomedical research,preventive medicine, public health, clinical trials,and medical imaging.Kwang Gi Kim received his M.S and Ph.D inPhysics and Biomedical Engineering from Pohanguniversity of science & technology and SeoulNational University, Seoul, Republic of Korea,respectively. Since then, he has worked for theResearch Assistance Professor at Seoul NationalUniversity, Chief Researcher at National CancerCenter, Republic of Korea.He currently works for Professor at Department ofBiomedical Enginieering in Gachon University and Director of MedicalDevices R&D Center in Gachon University Gil medical Center,Incheon, Republic of Korea, respectively.His interests are Biomedical Engineering, Surgical Robot Technique,Optical Diagnosis & Treatment Technique, Opto-medical Spectroscopy,Medical 3D Printing Technique, and AI Treatment Technique.Yong-Cheol Yoon received his M.D and Ph.D inorthopedics at Korea University, Seoul, Republicof Korea. He currently works for Professor atOrthopedic Trauma Division, Trauma Center,Gachon University College of Medicine, Incheon,Republic of Korea.90
Figure 6. Surgical case of LCP and locking screw and 3D CAD model. III. R ESULTS A. Finite Element Model . Figure 7. A 3 parts fracture (surgical neck of humerus and greater tubercle) and final two type (model A: with calcar screw, model B: without calcar screw) of 3D CAD model for FEA.
Finite element analysis DNV GL AS 1.7 Finite element types All calculation methods described in this class guideline are based on linear finite element analysis of three dimensional structural models. The general types of finite elements to be used in the finite element analysis are given in Table 2. Table 2 Types of finite element Type of .
Figure 3.5. Baseline finite element mesh for C-141 analysis 3-8 Figure 3.6. Baseline finite element mesh for B-727 analysis 3-9 Figure 3.7. Baseline finite element mesh for F-15 analysis 3-9 Figure 3.8. Uniform bias finite element mesh for C-141 analysis 3-14 Figure 3.9. Uniform bias finite element mesh for B-727 analysis 3-15 Figure 3.10.
1 Overview of Finite Element Method 3 1.1 Basic Concept 3 1.2 Historical Background 3 1.3 General Applicability of the Method 7 1.4 Engineering Applications of the Finite Element Method 10 1.5 General Description of the Finite Element Method 10 1.6 Comparison of Finite Element Method with Other Methods of Analysis
2.7 The solution of the finite element equation 35 2.8 Time for solution 37 2.9 The finite element software systems 37 2.9.1 Selection of the finite element softwaresystem 38 2.9.2 Training 38 2.9.3 LUSAS finite element system 39 CHAPTER 3: THEORETICAL PREDICTION OF THE DESIGN ANALYSIS OF THE HYDRAULIC PRESS MACHINE 3.1 Introduction 52
Finite Element Method Partial Differential Equations arise in the mathematical modelling of many engineering problems Analytical solution or exact solution is very complicated Alternative: Numerical Solution – Finite element method, finite difference method, finite volume method, boundary element method, discrete element method, etc. 9
3.2 Finite Element Equations 23 3.3 Stiffness Matrix of a Triangular Element 26 3.4 Assembly of the Global Equation System 27 3.5 Example of the Global Matrix Assembly 29 Problems 30 4 Finite Element Program 33 4.1 Object-oriented Approach to Finite Element Programming 33 4.2 Requirements for the Finite Element Application 34 4.2.1 Overall .
The Finite Element Method: Linear Static and Dynamic Finite Element Analysis by T. J. R. Hughes, Dover Publications, 2000 The Finite Element Method Vol. 2 Solid Mechanics by O.C. Zienkiewicz and R.L. Taylor, Oxford : Butterworth Heinemann, 2000 Institute of Structural Engineering Method of Finite Elements II 2
Nonlinear Finite Element Method Lecture Schedule 1. 10/ 4 Finite element analysis in boundary value problems and the differential equations 2. 10/18 Finite element analysis in linear elastic body 3. 10/25 Isoparametric solid element (program) 4. 11/ 1 Numerical solution and boundary condition processing for system of linear
